/**
 * SharePoint MegaMenu for Classic Pages
 * Version: 1.0.2
 * 
 * This version uses standalone services that replicate the SPFx logic
 * without requiring the SharePoint Framework.
 * 
 * Prerequisites:
 * 1. megamenu-services-standalone.js must be loaded first
 * 2. MegaMenu.css must be included
 * 3. SP.js and SP.Taxonomy.js must be available
 * 
 * Usage:
 * <link rel="stylesheet" href="/SiteAssets/megamenu/MegaMenu.css" />
 * <script src="/SiteAssets/megamenu/megamenu-services-standalone.js"></script>
 * <script src="/SiteAssets/megamenu/megamenu-classic.js"></script>
 */

(function() {
    'use strict';

    var MEGAMENU_UCA_ID = 'abc3361f-bb2d-491f-aba3-cd51c19a299b'; // Same as in MegaMenuApplicationCustomizer.ts
    
    var config = window.MegaMenuConfig || {
        containerId: 's4-titlerow',
        debug: false
    };

    function log(message, data) {
        if (config.debug && console && console.log) {
            console.log('[MegaMenu Classic] ' + message, data || '');
        }
    }

    // Wait for dependencies: SharePoint JSOM, Taxonomy, and our standalone services
    function waitForDependencies(callback) {
        if (typeof SP !== 'undefined' && 
            SP.SOD && 
            typeof SP.Taxonomy !== 'undefined' &&
            typeof window.MegaMenuServices !== 'undefined' &&
            document.readyState === 'complete') {
            callback();
        } else {
            setTimeout(function() { waitForDependencies(callback); }, 100);
        }
    }

    // Classic SharePoint context wrapper
    function createClassicContext() {
        return {
            pageContext: {
                site: {
                    absoluteUrl: _spPageContextInfo.siteAbsoluteUrl
                },
                web: {
                    absoluteUrl: _spPageContextInfo.webAbsoluteUrl,
                    permissions: {
                        hasPermission: function(permission) {
                            return _spPageContextInfo.isSiteAdmin === true;
                        }
                    }
                }
            }
        };
    }

    // Configuration reader using REST API (same logic as MegaMenuSettings.ts)
    function readMegaMenuConfiguration(callback) {
        log('Reading MegaMenu configuration from UserCustomAction...');
        
        var restUrl = _spPageContextInfo.siteAbsoluteUrl + 
            "/_api/site/userCustomActions?$filter=ClientSideComponentId eq guid'" + MEGAMENU_UCA_ID + "'";
        
        fetch(restUrl, {
            method: 'GET',
            headers: {
                'Accept': 'application/json;odata=nometadata'
            }
        })
        .then(function(response) {
            if (!response.ok) {
                throw new Error('HTTP ' + response.status + ' - ' + response.statusText);
            }
            return response.json();
        })
        .then(function(data) {
            if (data && data.value && data.value.length > 0) {
                var uca = data.value[0];
                try {
                    var props = JSON.parse(uca.ClientSideComponentProperties);
                    log('Configuration found', props);
                    callback(props);
                } catch (e) {
                    log('Error parsing UserCustomAction properties: ' + e.message);
                    callback({ termSetName: 'Navigation', cssUrl: '' });
                }
            } else {
                log('No UserCustomAction found - using defaults');
                callback({ termSetName: 'Navigation', cssUrl: '' });
            }
        })
        .catch(function(error) {
            log('Error reading configuration: ' + error.message);
            callback({ termSetName: 'Navigation', cssUrl: '' });
        });
    }

    // Load external CSS (same as SPFx version)
    function loadExternalCSS(cssUrl) {
        if (!cssUrl) return;
        
        var link = document.createElement('link');
        link.rel = 'stylesheet';
        link.type = 'text/css';
        link.href = cssUrl;
        link.onerror = function() {
            log('Failed to load external CSS: ' + cssUrl);
        };
        link.onload = function() {
            log('External CSS loaded successfully: ' + cssUrl);
        };
        document.head.appendChild(link);
    }

    // Main initialization
    function initMegaMenu() {
        log('Initializing MegaMenu for classic SharePoint...');
        
        // Check if services are available
        if (!window.MegaMenuServices) {
            console.error('[MegaMenu] Standalone services not found! Please include megamenu-services-standalone.js first.');
            return;
        }
        
        readMegaMenuConfiguration(function(props) {
            log('Using configuration:', props);
            
            // Load external CSS if specified
            if (props.cssUrl) {
                loadExternalCSS(props.cssUrl);
            }
            
            // Create context
            var context = createClassicContext();
            
            // Create taxonomy service using standalone implementation
            var taxonomyService = new window.MegaMenuServices.TaxonomyNavigationService(
                context, 
                props.termSetName
            );
            
            // Load menu items
            taxonomyService.getMenuItems()
                .then(function(menuItems) {
                    log('Menu items loaded:', menuItems);
                    
                    // Find target container
                    var container = document.getElementById(config.containerId);
                    if (!container) {
                        log('Container not found: ' + config.containerId + '. Creating fallback container.');
                        // Create fallback container at top of page
                        container = document.createElement('div');
                        container.id = 'megamenu-fallback-container';
                        document.body.insertBefore(container, document.body.firstChild);
                    }
                    
                    // Create menu wrapper
                    var menuWrapper = document.createElement('div');
                    menuWrapper.className = 'megamenu-classic-container';
                    
                    // Insert menu wrapper
                    if (container.nextSibling) {
                        container.parentNode.insertBefore(menuWrapper, container.nextSibling);
                    } else {
                        container.parentNode.appendChild(menuWrapper);
                    }
                    
                    // Create renderer using standalone implementation
                    var renderer = new window.MegaMenuServices.MegaMenuRenderer(
                        context,
                        menuItems,
                        function(updatedProps) {
                            log('Properties updated (not persisted in classic mode):', updatedProps);
                        }
                    );
                    
                    // Render the menu
                    renderer.render(menuWrapper);
                    
                    log('✅ MegaMenu rendered successfully!');
                })
                .catch(function(error) {
                    console.error('[MegaMenu] Error loading menu items:', error);
                    
                    // Show error message to user
                    var container = document.getElementById(config.containerId);
                    if (container) {
                        var errorDiv = document.createElement('div');
                        errorDiv.style.cssText = 'background:#ffebee;color:#c62828;padding:10px;border:1px solid #ef5350;margin:5px 0;';
                        errorDiv.innerHTML = '<strong>MegaMenu Error:</strong> ' + error.message + 
                                          '<br><small>Check browser console for details.</small>';
                        
                        if (container.nextSibling) {
                            container.parentNode.insertBefore(errorDiv, container.nextSibling);
                        } else {
                            container.parentNode.appendChild(errorDiv);
                        }
                    }
                });
        });
    }

    // Bootstrap function
    function bootstrap() {
        log('Bootstrapping MegaMenu...');
        
        // Wait for SharePoint JSOM to be ready
        if (typeof SP === 'undefined' || !SP.SOD) {
            setTimeout(bootstrap, 100);
            return;
        }
        
        // Load required SharePoint libraries
        SP.SOD.executeFunc('sp.js', 'SP.ClientContext', function() {
            SP.SOD.executeFunc('sp.taxonomy.js', 'SP.Taxonomy.TaxonomySession', function() {
                // Wait for all dependencies and initialize
                waitForDependencies(function() {
                    initMegaMenu();
                });
            });
        });
    }

    // Auto-start based on DOM state
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', bootstrap);
    } else {
        // DOM already loaded
        setTimeout(bootstrap, 100);
    }

    // Expose public API
    window.MegaMenuClassic = {
        init: initMegaMenu,
        bootstrap: bootstrap,
        config: config,
        
        // Utility methods
        setConfig: function(newConfig) {
            Object.assign(config, newConfig);
        },
        
        reload: function() {
            // Remove existing menu and reload
            var existing = document.querySelector('.megamenu-classic-container');
            if (existing) {
                existing.remove();
            }
            initMegaMenu();
        }
    };

    log('MegaMenu Classic wrapper loaded. Waiting for dependencies...');

})();